Rapid emergence of antibiotic-resistant bacteria has made it harder for us to combat infectious diseases and to develop new antibiotics. The clustered regularly interspaced short palindromic repeats – CRISPR-associated (CRISPR-Cas) system, as a bacterial adaptive immune system, is recognized as one of the new strategies for controlling antibiotic-resistant strains. The programmable Cas nuclease of this system used against bacterial genomic sequences could be lethal or could help reduce resistance of bacteria to antibiotics. Therefore, this study aims to review using the CRISPR-Cas system to promote sensitizing bacteria to antibiotics. We envision that CRISPR-Cas approaches may open novel ways for the development of smart antibiotics, which could eliminate multidrug-resistant (MDR) pathogens and differentiate between beneficial and pathogenic microorganisms. These systems can be exploited to quantitatively and selectively eliminate individual bacterial strains based on a sequence-specific manner, creating opportunities in the treatment of MDR infections, the study of microbial consortia, and the control of industrial fermentation.

There has been excessive rate of use of antibiotics to fight Pseudomonas aeruginosa (P. aeruginosa) infections worldwide, which has consequently caused the increased resistance to multiple antibiotics in this pathogen. Due to the widespread resistance and the current poor effect of antibiotics consumed to treat P. aeruginosa infections, finding some novel alternative therapeutic methods are necessary for the treatment of infections. The P. aeruginosa biofilms can cause severe infections leading to the increased antibiotic resistance and mortality rate among the patients. In this regard, there are no approaches that can efficiently manage these infections; therefore, novel and effective antimicrobial and antibiofilm agents are needed to control and treat these bacterial infections. Quorum sensing inhibitors (QSIs) or quorum quenchings (QQs) are now considered as potential therapeutic alternatives and/or adjuvants to the current failing antibiotics, which can control the virulence traits of the pathogens, so as a result, the host immune system can quickly eliminate bacteria. Thus, the aims of this review article were presenting a brief explanation of the research reports on the natural and synthetic QSIs of P. aeruginosa, and the assessment of the current understanding on the QS mechanisms and various QQ strategies in P. aeruginosa.

Purpose: Many antimicrobial medications are available to combat infections. However, the indiscriminate use of antibiotics has produced antibiotic resistance in the case of many bacterial pathogens. This study focuses on the development of nanoparticles (NPs) that enhance the in vitro antibiotic activity of vancomycin against multi-drug resistant (MDR) organisms. Methods: Spherical shaped thioglycolic acid-stabilized silver nanoparticles (TGA-AgNPs) were prepared by using a simple chemical reduction method. Then, vancomycin was conjugated to the terminal carboxyl of TGA in the presence of N-Hydroxysuccinimide (NHS) and N-(3-dimethylaminopropyl)-N’-ethylcarbodiimide hydrochloride (EDC). Afterwards, the antibacterial activity of these nanoconjugates was examined by using the minimum inhibitory concentration (MIC) assay against MDR bacteria. Results: The rate of vancomycin bound to the AgNPs was 19.6%. The MIC values of vancomycin (Van)-capped AgNPs against tested pathogens were in the range of (3.2, 1.6, 0.8, 0.4, 0.2, 0.1, 0.05, and 0.025 µl/ml). The MIC was 0.1 µg/ml for VRE, MIC≤0.02 µg/ml for MRSE, and 0.05 µg/ml for S. aureus. The MIC corresponded to the MBC for all bacterial species. Conclusion: This study indicated that some antimicrobial agents like vancomycin can be conjugated with AgNPs. This can lead to increased antimicrobial activity against MDR microorganisms.

The medicinal characteristics of garlic’s (Allium sativum L.) dynamically bioactive constituents such as alliin, allicin, ajoene, S-allyl-cysteine, S-trityl-L-cysteine, diallyl sulfide, and S-allylmercaptocysteine, have gained a lot of scientific attention from a large number of investigators who have occupied the related pre-clinical and clinical studies, as well as in the industrial sector. The outcomes from basic investigations demonstrated that, depending on the type of food processing, the presence of bioactive compounds in the matrix of garlic have a coherent and direct relation with the appearance/development of health-promoting effects in the host. Besides, it can be acknowledged that at present spectroscopic and chemometric techniques are powerful tools to detect fraud, prevent criminal activities of fraudsters, and ensure food chain safety, and future studies should lead to further progress, such as portable and hand-held spectroscopy devices for rapid on-site analysis, in this field. There have been also many issues on the effects of processing on garlic’s bioactive compounds, potential toxicities, pharmacokinetics, and safety profile of these elements that should be studied to validate the health advantages of garlic in humans. In this review, the outcomes of recent experimental and clinical reports are reviewed and metabolism pathway, bioavailability, biological/therapeutically effects, food-related applicability, methods of adulteration detection, potential toxicities, and safety profile of garlic’s derived bio-compounds are discussed.

The aim of this study was to characterize virulence determinants and antibiotic resistance profiles in enterococci obtained from various clinical sources in the northwest of Iran. A total of 160 enterococcal clinical isolates from various wards of University Teaching Hospitals were collected and specified by biochemical test, from September 2014 to July 2015. Identification of enterococci was confirmed by multiplex PCR in the genus and species level. Antibiotic resistance properties and virulence determinants were examined by phenotypic and molecular methods. Of 160 enterococcal isolates, 125 (78.12%) and 35 (21.88%) isolates were identified as Enterococcus faecalis and Enterococcus faecium , respectively. The most common antibiotic nonsusceptible pattern observed was resistance toward rifampicin [ n = 122 (76.25%)] followed by erythromycin [ n = 117 (73.12%)]. Among all isolates, gel E [ n = 140 (87.5%)], cpd [ n = 137 (85.6%)], and asa 1 [ n = 118 (73.8%)] were the most prevalent virulence genes studied. Thirty isolates (11 E. faecalis , 19 E. faecium ) were found to be resistant to vancomycin, with minimum inhibitory concentration of ≥256 μg/ml. Twenty-seven isolates carried the van A gene, whereas none of the isolates carried van B. E. faecalis had a considerable ability to show virulence genes and drug resistance. Emergence of antibiotic-resistant enterococci and the high prevalence of virulence traits in our study could be regarded as an alarming situation.

Carbapenems have been considered as last line antibiotics for treatment of multidrug-resistant (MDR) Acinetobacter baumannii but carbapenem resistant A. baumannii has been increased during the last decade in many parts of the world. OXA-type β-lactamase enzymes are the most common cause of carbapenem resistance in A. baumannii and presence of IS Aba1 in upstream of these genes may increase the expression of these OXA genes. The aim of this study was to determine, for the first time, the antibiotic resistance pattern and prevalence of OXA type β-lactamases among nosocomial A. baumannii isolates from northwest of Iran. A total of 100 A. baumannii isolates were recovered from hospitalized patients in a university hospital in northwest of Iran. Sixty-two percent of isolates were resistant to imipenem. All isolates carried bla _OXA-51 -like gene. Among imipenem resistant isolates, 88.7% carried bla _OXA-23 -like, 1.6% carried bla _OXA-40 -like, and 3.2% had bla _OXA-58 -like resistance genes. Ninety percent of isolates contained IS Aba1 element and in 74.2% of imipenem resistant isolates, IS Aba1 was located in upstream of bla _OXA-23 -like. The results of this study demonstrated high prevalence of OXA-type carbapenemase among MDR A. bumanii in the Northwest of Iran.